1. Field of the Invention
This invention pertains to fiber-forming melt-spinnable aromatic polyesters and to high modulus filaments thereof.
2. Description of the Prior Art
A class of aromatic polyesters that form optically anisotropic melts from which oriented filaments can be melt-spun has been described in U.S. Pat. No. 4,118,372 to Schaefgen et al. Other aromatic polyesters that have this property are disclosed in U.S. Pat. No. 4,066,620. The polyesters which are described in the aforementioned references are derived primarily from para-oriented dihydric phenols and para-oriented aromatic dicarboxylic acids. Filaments that are melt-spun from such polyesters can be heat treated to high tenacity and modulus.
This invention provides different aniso-tropic-melt-forming polyesters which can be melt-spun into filaments of high as-spun modulus [e.g., greater than 200 g/denier (177 dN/tex)]. The novel filaments can also be heat treated to increase their tenacities, preferably to a level in excess of 10 g/denier (8.84 dN/tex), while retaining moduli in excess of 200 g/denier (177 dN/tex).